The primary goal of this research is to extend the theoretical basis for designing and maintaining programming languages. The ultimate goal of this line of research is to give programming language designers more ability to design languages which can be methodically extended in a variety of directions (e.g., the introduction of parallelism) and implemented on a variety of machines while preserving the correctness of existing programs. To achieve this goal, a number of basic conceptual issues, and some case studies will be examined to investigate the practical importance of the theory. The conceptual issues include the relations between operational, denotational, and axiomatic semantics, the definitional and conceptual power of structured operational semantics, and expressiveness of various sequential and parallel primitive operations. The case studies may include the design of parallel extensions of ML.
